Andrew W. Lo, the MIT finance professor and hedge fund manager, wants to bring Wall Street-style financial­ engineering to a crucial social need: curing cancer. Named this year as one of Time magazine’s 100 most influential people in the world, Lo runs an investment firm in Cambridge called AlphaSimplex Group, with $3 billion in assets. He is known for his “adaptive markets” financial theory, which maintains that prices and investors are not always rational.